Interlock mechanism



y 0, 1956 A. L. HUEHNEL INTERLOCK MECHANISM 2 Sheets-Sheet 1 Filed March23, 1953 IN V EN TOR. flZ 14 1 Zea 4Z4 Mei/{:1

177' IZIWYE K United States Patent O INTERLOCK MECHANISM Alwin LeopoldHuehnel, Milwaukee, Wis., assignor to Square D Company, Detroit, Mich, acorporation of Michigan Application March 23, 1953, Serial No. 344,147 6Claims. (Cl. 2927) This invention relates to a mechanism whichinterlocks the door locking mechanism of a cabinet with exteriorlymanipulated mechanism for operating a device such as an electric circuitbreaker or switch mounted within the cabinet.

An object of the invention is to provide a simple, rugged andinexpensive interlock mechanism between the operating mechanism of adevice enclosed within a cabinet and the locking mechanism for the doorof the cabinet.

Another object of the invention is the provision of an interlockmechanism in accordance with the preceding object in which it isimpossible to jamthe mechanism by a simultaneous manual manipulation ofthe door and device operating handles.

Another object of the invention is an interlock mechanism in accordancewith the preceding objects in which any number of devices may beinterlocked with the door locking mechanism and in which the devices maybe located in various locations relative to the door with simpleadjustments.

Other objects and features of the invention will be readily apparent tothose skilled in the art from the specification and appended drawingsillustrating certain preferred embodiments in which:

Figure l is a partial front elevational view of a cabinet door showingexterior handles for manipulation.

Figure 2 is an internal perspective view of the interlock mechanism withthe parts shown with the interlock disabled.

Figure 3 is a figure similar to Figure 2 with the interlock mechanism inoperative position.

Figure 4 is a perspective view showing the interlock mechanism in asecond operative position.

The interlock mechanism of the present invention is applied to aconventional cabinet 1 having a hinged front door 2 provided at theexterior thereof with front manipulable handles 3 and 4, the handle 3operating the door locking and unlocking mechanism and the handle 4operating a device such. as an electric circuit breaker or disconnectswitch within the cabinet. The handle 4 is provided with a hub 5 havingslots in its side walls into which may be inserted a locking bar 6 tolock the handle in various positions.

The handle 3 is mounted on a shaft 7 extending through the door 2 andcarrying at the back of the door a latch member 8 connected to a pair ofoppositely directed shoot bolts 9 and 11 adapted to engage the cabinetadjacent the top and bottom of the door opening to latch door closed.Latch member 8 has a rigid arm 12 mounted thereon in a position tocooperate with a latch 13 adjustably mounted on a pivoted lever 14. Onthe back wall of the door 2 is mounted a four-sided bracket 15 havingthe lever 14 pivoted in its opposite side walls. A bracket 16 is mountedon one side wall of the bracket 15 and a rod 17 extends through openingsin the bracket 16 and in the top wall of the bracket 15, being thusguided for rectilinear movement in a substantially vertical direction asshown. A spring 18 biases rod 17 in the downward direction to en-2,754,143 Patented July 10, 1956 gage the lower end of the rod with anarm 19 on the lever 14 The rod 17 extends through an opening in a flange21 integral with one arm of a bell-crank lever 22 pivoted at 20 on theback of the door. The flange 21 engages an adjustable stop 10 on the rod17 in one direction. A lever 23 is pivoted intermediate its ends at 24on the back of the cover 2 and is guided for limited rotary movement ina plane parallel to the door by a bracket 25. A spring 26 between thelever 23 and bracket 25 biases the lever for rotation in acounterclockwise direction as viewed in the drawings. A pair of anglebrackets 27 and 28 are pivotally mounted on the levers 22 and 23 and areinterconnected by means of a rod 29 adjustably engaging therewith.

The interlock mechanism has been shown in a cabinet containing anelectric circuit breaker 31 having suitable operating mechanisminteriorly and exteriorly of its casing, this including a rotatableoperating shaft 32 terminating at its outer end in a male member 33adapted to cooperate, when the door 2 is closed, with a female socket 34rigidly mounted upon the shaft carrying the handle 4. Also mounted onthis shaft is an arm 35, the handle 4, socket 34 and arm 35 beingrigidly connected together for movement as a unit. The arm 35 isprovided adjacent its end with a roller 36 adapted to cooperate with acam surface 37 located on a lower edge of the lever 23. The cam surface37 is provided with an indexing notch 38 engaged by the roller 36 in theposition of the parts shown in Figure 2.

The operation of the interlock mechanism will now be described:

With the door 2 member 33 so as shaft 32 to effect closed, the socket 34engages the male to join the exterior handle 4 to the rotation thereofand operation of the mechanism within the circuit breaker 31. The partsas shown in Figure 3 are in the position with the circuit breaker On toclose the circuit therethrough. In this position, the handle 4 has beenrotated into its farthest counterclockwise position, as viewed in Figure1, which moves the circuit breaker operating means shown in Fig ures 2through 4 to their farthest clockwise position, this being shown inFigure 3 where the roller 36 on the arm 35 has been rotated to aposition where it entirely disengages the cam 37 on the lever 23. Thelever 23 has thus been freed to move in a counterclockwise directionunder the bias of the spring 26, its ultimate position being limited bythe bracket 25. As the lever 23 moved to its counterclockwise position,the bell-crank lever 22 rotated in a clockwise direction and the rod 17was raised by the engagement of the flange 21 with the stop 10 on therod, the spring 26 being sufficiently strong relative to spring 18 toaccomplish this movement. In the upward position of the rod 17, thelever 14 rotated into locking position under either the bias of gravityor the bias of a spring, not shown, which may be used if desired wherethe bias of gravity is not effective. With the parts in the positiondescribed, the arm 12 engages with the latch 13 if the door handle ismanipulated, thus preventing rotation of the latch member 8 andpreventing withdrawal of the shoot bolts 9 and 11.

When the operating handle 4 is moved to the Oif position, the partsassume the position shown in Figure 2 with the roller 36 engaged in theindexing notch 38'on theof gravity or its spring, if used. In this lowerposition of the rod 17, the latch 13 has been moved out of obstructingrelation to the arm 12 and the handle 3 may be freely rotated to rotatethe latch member 8 and retract the shoot bolts 9 and 11 to permit thedoor 2 to be opened, this opening movement disengaging socket 34 frommale member 33.

In the operation of devices within the cabinet, the handle 4 may assumea position beyond the Off position, which third position may in the caseof electric circuit breakers be utilized to effect a resetting of themechanism after an automatic trip. In this third position of the handlethe circuit breaker contacts are maintained disengaged and the roller 36has been moved below the notch 38 as shown in Figure 4. In this positionof the handle, the lever 23 has rotated in a counterclockwise directionsufiiciently to move the rod 17 upwardly to permit the lever 14 to swingtoward. the door under its bias.

This again places the latch 13 in obstructing position with respect tothe arm 12 and if the handle 4 is locked in this third or resettingposition, the circuit breaker contacts Will be maintained Off while thecabinet door is locked closed.

With the interlock mechanism of the present invention, it is seen thatshould the door handle be left in the open position when the circuitbreaker is moved closed, the door handle will lock automaticallythereafter as it is turned to closed position, the lever 14 swingingaway from the door to permit passage of the arm 12 as the lower edge ofthe arm engages the inclined edge of the latch 13.

It is further seen that with the provision of operation of the latch 13and lever 14 through the spring 18 which overcomes the bias on the lever14, no jamming can occur from forcing the exterior operating handles. Itis also seen that a number of mechanisms may be mounted to cooperatewith the rod 17 and it will be necessary for all of the devicesassociated with the mechanisms to be in Off position before the rod 1'7will be permitted to move downwardly to disable the interlock.

Also, it is seen that the location of the device within the cabinet andadjustments for inaccuracies may be readily made through a simplevariation in the effective lengths of the rods 17 and 29.

While certain preferred embodiments of the invention have beenspecifically disclosed, it is understood that the invention is notlimited thereto, as many variations will be readily apparent to thoseskilled in the art and the invention is to be given its broadestpossible interpretation within the terms of the following claims:

What is claimed is:

1. An interlock between door locking mechanism and operating mechanismfor a device installed behind the door comprising door locking mechanismbehind the door, an operating handle on the front of the door foroperating said door locking mechanism, a second operating handle on thefront of the door for operating a device installed behind the door, alatch mounted on the back of the door and biased into a positionobstructing unlocking movement of the door locking mechanism, a membermounted on the back of the door and biased to move said latch againstits bias into non-obstructing position, a lever pivoted at the back ofthe door and engaging said member in one direction only to move itagainst its bias, a second lever pivoted on the back of the door andbiased to move said first lever in a direction to move the memberagainst its bias, and means for moving said second leveragainst its biasin response to movement of the device operating handle so as to efiectmovement of said latch into obstructing and non-obstructing position inresponse to the chain of movement through said device operating handle,second lever, first lever, and member.

2. An interlock as defined in claim 1 in which the point of engagementof the first lever and member is adjustable to compensate for variationin the relation of the device and door locking member.

3. An interlock between door locking mechanism and operating mechanismfor a device installed behind the door comprising door locking mechanismbehind the door, an operating handle on the front of the door foroperating said door locking mechanism, a second operating handle on thefront of the door for operating a device installed behind the door, alatch mounted on the back of the door and biased into a positionobstructing unlocking movement of the door locking mechanism, a membermounted on the back of the door and biased to move said latch againstits bias into non-obstructing position, a lever pivoted on the back ofsaid door and operable to move said member against its bias and meansresponsive to rotation of said device operating handle for rotating saidlever to move the member to efiect movement of the latch into and out ofobstructing position.

4. An interlock mechanism for the door of an enclosing cabinet havingmeans at the exterior of the door for operating a device enclosed withinthe cabinet including manipulable means at the exterior of the door foreffecting operation of the door-locking mechanism disposed behind thedoor, a latch pivoted on the back of the door and rotatable toward andaway from the door into and out of position obstructing the unlockingmovement of the door locking mechanism, a reciprocal rod biased torotate said latch away from the door into unlatching position, said rodbeing guided for rectilinear movement parallel to the door and providedwith biasing means for moving it toward latch disengaging position, saidrod engaging the latch only in its biased direction, a first leverpivoted at the back of the door and engaging said rod in one directiononly to move its against its bias, a second lever pivoted at the back ofthe door, means interconnecting said levers, means biasing said secondlever to rotate said first lever in a direction to move the rod againstits bias, manipulable means at the ex terior of the door and extendingthereto to efiect operation of a device within the cabinet, and an armrotatable by said manipulable means in a plane parallel to the door andengaging said second lever to effect movement thereof against its biasto enable the rod to move under its bias to disable the latch and permitunlocking movement of the door locking mechanism.

5. An interlocking mechanism defined in claim 1 in which the arm isprovided with a roller engaging a cam surface on said lever to effectmovement thereof against its bias, the cam surface including an indexingnotch receiving the roller to hold the manipulable means in an indexedposition corresponding to the latch disabled position of the interlockmechanism.

6. An interlocking mechanism as defined in claim 4 in which theengagement between said rod and first lever is adjustable and theconnecting means between said first and second levers is adjustablewhereby to compensate for variations in the locations of the device anddoor locking mechanisms.

References Cited in the tile of this patent UNITED STATES PATENTS2,048,377 Robinson July 21, 1936 2,090,517 Moyer Aug. 17, 1937 2,166,058Kirk July 11, 1939 2,276,019 Ching Mar. 10, 1942 2,363,364 Rugg Nov. 21,1944 2,477,396 Weiskopf July 26, 1949 2,507,822 Sherrill May 16, 1950

